This invention comprises a pulverulent composition for dyeing and bleaching human hair having improved properties, and a process for the preparation of said composition.
Conventional compositions for brightening or bleaching of human hair contain at least one solid peroxide, especially a persulfate, and a pulverulent carrier. Before application onto the hair, this powder is mixed with a 6% to 12% solution of hydrogen peroxide. Examples of such compositions are disclosed in the cosmetic literature, e.g. K. Schrader, "Grundlagen und Rezepturen der Kosmetika", 2nd Ed. (1989, Huthig Buchverlag), pp. 815 to 823.
The properties of these bleaching powders, however, are not yet satisfactory. On the one hand they develop dust when used, on the other hand their dosage cannot be measured exactly enough so as to affect the desired bleaching result.
The same refers to the well-known pulverulent compositions for direct dyeing of human hair on the basis of natural dyestuffs and direct dyes, which are mixed with water before application.
It has now been found that a pulverulent composition for hair bleaching and dyeing, which does not show the disadvantages mentioned, can be obtained if the composition comprises at least one bleaching compound, preferably a solid peroxide compound, or at least one pulverulent direct dye, along with a pulverulent carrier such as silica, for example pyrogenic silica or diatomasceous earth or starch, and about 5% to about 30% by weight of at least one wax or wax-like substance having a flow point between about 40.degree. C. to about 130.degree. C.
The powder thus prepared and agglomerated or coated is not only completely dustless or at least substantially free of uncoated or unagglomerated dust-forming particles, but also easily flowable, it allows precise dosage and, therefore, convenient mixing with water or a hydrogen peroxide solution before its application onto human hair.
These properties can be improved in a preferred embodiment of the invention by the addition of low quantities of a surfactant to the powder, e.g. a long-chain alkyl sulfate or alkyl ether sulfate, a fatty acid alcohol ethoxylate, an alkylphenol ethoxylate, a polyoxyethylene sorbitan monooleate, laurate or stearate or glycerol-mono- or distearate.
Granulated hair bleaching powders are already known from German Patent Application No. 2,023,922; those are made from per salts and water-soluble binding agents, preferably polyvinyl pyrrolidone. These granules, however, cannot solve the problems indicated above, because they are relatively large-sized particles in the range of millimeters rather than microns so that problems of homogeneous mixing with aqueous hydrogen peroxide arise on the one hand; on the other hand the preparation of these products is relatively expensive in comparison to the bleaching and dyeing powders of the invention which are preferably prepared by melting the wax or wax-like substance together with the solid bleaching compound or the mixture comprising the dyeing compound, or by spraying it onto such mixtures.
The same applies to the granules disclosed in German Patent Application No.4,026,235, the products of which practically correspond with those described in German Patent Application No.2,023,922 previously mentioned.
In principle all natural and synthetic waxes having a flow point within an optimal range of 40.degree. C. to 130.degree. C., preferably from 50.degree. C. to 100.degree. C., are suitable provided that they do not affect the dissolving or dispersing properties of the composition in the aqueous hydrogen peroxide solution.
Suitable waxes are especially polyethylene glycol waxes having a molecular weight between about 600 and 12,000, particularly from 1,500 to 10,000, wherein mixtures of polyethylene glycol waxes of higher or lower molecular weight may also be used, provided the flow point of the mixture is within the range of the invention.
An example for such a composition is a combination of about 10% to 30%, preferably about 20% by wt. of a polyethylene glycol having a molecular weight of about 400 to about 800, particularly about 600, and about 70 to 90, preferably about 80 parts by weight of a polyethylene glycol wax having a molecular weight of about 9,000 to 11,000, preferably about 10,000.
Other suitable waxes are for instance esters of C.sub.16 -C.sub.32 -fatty acids and C.sub.12 -C.sub.32 -fatty alcohols such as cetyl palmitate, mineral waxes, beeswax, shellac wax, (hydrogenated) triglycerides, lanolin and the derivatives thereof, spermaceti, paraffin waxes, microparaffins, ozokerite, ceresin wax, candelilla wax, carnauba wax, montan wax, Japan wax, sugar cane wax, cork wax, guarama wax, astrolatum, petrolatum, hydrogenated jojoba waxes, montan ester waxes, mixed waxes containing emulsifiers, such as the commercial products "Tegin.RTM.", "Lanette.RTM.", "Cutina.RTM.", "Dehymuls.RTM.", and "Emulgade.RTM.", fatty alcohols having a waxy consistency, fatty acid esters of polyvalent alcohols such as glycerol behenate, glycerol palmitate or stearate, polyglycol glycerides, silicone waxes, higher paraffins, etc.